Since their discovery in 1968, boron dipyrromethenes have been synthesized by complex methodologies which involve several steps, long reaction times, tedious purification, and tow yields, As time passed, techniques for obtaining these compounds were improved. While compounds exhibiting fluorescence in a large range of colors under UVC light (280 nm-200 nm) have been obtained, compounds exhibiting blue fluorescence and its nearby colors have not been reported. Ten years ago, Boyer and collaborators tried to synthesize blue boron dipyrromethenes (Heteroat. Chem. 4, 603 (1993) and Heteroat. Chem 4, 609 (1993)). In these experiments, the chromophore structure was drastically modified to decrease dislocation, yet Boyer still did not obtain highly fluorescent derivatives or compounds having high laser efficiencies.
There are no reports of boron dipyrromethenes with blue florescence. Other blue emitting compounds are known, which have similar applications to the compounds according to the invention. However, as reported in WO 2005/118606 of Konno et al., these compounds are more complex molecules with a larger number of atoms than the inventive compounds and require very complicated synthesis processes which require more hours of laboratory work and more complex molecules. Such compounds emit at 470 nm with a low quantum yield not higher than φ=0.8 in tetrahydrofuran.
Miyawaki et al. (WO 2004/111236) reports proteins that fluoresce in the border area of the blue range (480 nm). However, this type of blue fluorescent protein is severely limited because its use is especially the biological area, is limited to certain mediums, and does not have a very high quantum yield (φ=0.68).
Finally, there are known compounds that are patented for laser use (see U.S. Pat. No. 3,857,793 of Pappalardo et al.). For example, perylene, which emits at 410 nm in cyclohexane and has a quantum yield of φ=0.94, is a 5 ring compound. P-terphenyl has an emission at 290 nm in cyclohexane and a 0.93 quantum yield. 9,10-diphenylanthracene is a compound with a high 1.0 quantum yield, but this compound fluoresces at 350 nm, an emission which does not correspond to blue. Accordingly, none of these compounds that are known for use in lasers emits within the blue fluorescent range.